Improving Gate Reliability of 6-In E-Mode GaN-Based MIS-HEMTs by Employing Mixed Oxygen and Fluorine Plasma Treatment

Abstract

Robust and reliable gate scheme is crucial in developing the enhancement-mode (E-mode) AlGaN/GaN metal–insulator–semiconductor (MIS)-high electron mobility transistors (HEMTs). This work reports on a method of mixed oxygen and fluorine plasma pretreatment combined with selected bi-layer gate dielectrics to improve the performances of partially recessed-gate MIS-HEMTs. The fabricated E-mode HEMTs exhibit significantly boosted threshold voltage of 2.5 V and gate breakdown voltage of 26 V, as well as improved device reliability on 6-in wafer under both bias and temperature stresses. Remarkably reduced <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> shift is found even at 250 °C high temperature. Furthermore, measurements on gate breakdown lifetime show a ten-year lifetime of the fabricated devices when the gate bias is kept below 13.1 V which demonstrates a promising scheme in fabricating the E-mode HEMT products.